There might be some science behind how employers are using social media posts to screen applicants and hire employees.

According to recent survey by CareerBuilder.com, 39 percent of companies use social media sites to research job candidates, up only two percent from last year. Yet, there was a nine percent jump (from 34 to 43 percent) in the number of hiring managers who report using information found on a social media site to disqualify a candidate from consideration.

Among the types of disqualifying information found on social media sites:

Interestingly, North Carolina State University's Journal of Cyberpsychology, Behavior, and Social Networking just published an article entitled, "Big Five Personality Traits Reflected in Job Applicants' Social Media Postings." According to a press release announcing the article's publication, "Companies may have a fundamental misunderstanding of online behavior and, as a result, may be eliminating desirable job candidates."

To compile data for the article, researchers tested 175 people to measure the personality traits that companies look for in job candidates (such as conscientiousness, agreeableness and extraversion), and then surveyed their Facebook behavior to link it to the specific personality traits.

The findings were eye-opening:

There is no significant correlation between conscientiousness and Facebook posts about alcohol or drug use.

Extroverts are significantly more likely to post about drugs or alcohol of Facebook.

In other words, the 48 percent of the companies in the CareerBuilder survey that reported disqualifying a job candidate because of social media posts about drinking or drug use may have done themselves a disservice. That disservice might be compounded if the position for which the company is hiring favors extroverted personalities (such as a sales position).

All is not bad news from the NC State survey. Study participants who rated high on both agreeableness and conscientiousness were also very unlikely to "badmouth" other people on Facebook, including their former bosses. So, the one-third of companies in the CareerBuilder survey who reported disqualifying a job candidate for bad mouthing a previous employer are likely making a good hiring decision.

Stats are just stats, and should not be taken as the bible on the issue on which they are reporting. Indeed, there are reasons other than agreeableness and conscientiousness for which a company might consider disqualifying a candidate who posts about drug use or drinking. For example, I would question the judgment of anyone posting any info or pictures of drug use, and question the judgment of active job seekers posting photos or other information on excessive drinking.

These two surveys, however, make for an interesting juxtaposition, and show that there might be some science behind how employers are using social media posts to screen applicants and hire employees.

Moreover, regardless of how you use the information you find online, the guidance for the process you should be using to obtain the information remains the same—companies need to ensure that the information upon which they are making hiring decisions is lawful, and that appropriate screens are in place to prevent protected information (such as Equal Employment Opportunity information) from leaking into the hiring process.